The present invention relates to a hinge device, and particularly to a hinge device for pivotably connecting a display unit to a mainframe unit of a portable computer wherein the hinge device provides substantially a constant torque resistance at all positions in the arc of movement between various display unit open positions and the display unit closed position, and wherein the hinge device effectively retains lubrication grease therein so that the hinge device can have a smoother movement and a longer life.
A variety of hinge devices are used for rotatably coupling two articles together, such as a display unit and a mainframe unit of a portable computer. The display unit is required to be frequently opened or closed and to be positioned relative to the mainframe unit at any desired angle. However, the hinge device loses effectiveness after a period of use as it loses its ability to produce sufficient torque resistance to support the weight of the display unit. Such a conventional hinge device is disclosed in U.S. Pat. No. 5,574,252, as shown in FIG. 9. The hinge device comprises a pair of hinge members 10, an intermediate member 20 and a pair of helical springs 30. Each hinge member 10 has a cylindrical end 14. A blind hole 142 is coaxially defined in the cylindrical end 14 of a first hinge member 10, and an elongated boss 146 extends from the cylindrical end 14 of a second hinge member 10. The boss 146 extends through a through hole 246 defined in the intermediate member 20 and into the hole 142 of the cylindrical end 14, whereby the intermediate member 20 pivotally connects to the pair of hinge members.
No groove which can effectively reserve lubrication grease therein is defined in contact surfaces of the boss 146 and the intermediate member 20. The contact surfaces have a tendency to be damaged due to insufficient lubrication. Thus, the hinge device can not operate smoothly over a long lifespan. Furthermore, the hinge device provides different torque resistances at different positions in its operational arc during the closing and the opening of the display unit relative to the mainframe unit, resulting in a poor operational feel.
A main object of the present invention is to provide a hinge device which pivotably joins a display unit to a mainframe unit of a portable computer and has means to retain lubrication grease therein, thereby producing a hinge which operates smoothly.
Another object of the present invention is to provide a hinge device for pivotably joining a display unit and a mainframe unit of a portable computer which has substantially a uniform torque resistance at different positions in its operational arc to keep the display unit at a desired angle relative to the mainframe unit when the display unit is rotated away from the mainframe unit.
A hinge device in accordance with the present invention comprises a male hinge member fixed to a display unit of a portable computer and a female hinge member fixed to a mainframe unit of the portable computer. The male hinge member includes a pivoting rod at one end thereof, a first mounting plate at an opposite end thereof for mounting the male hinge member onto the portable computer and a shoulder between the pivoting rod and the first mounting plate. The pivoting rod has a first contacting section on an outer periphery thereof. The female hinge member includes a cylindrical body for receiving the pivoting rod and a second mounting plate laterally extending from an end of the body for mounting the female hinge member onto the portable computer. A separating slot is transversely defined in a periphery of the body, thereby defining a receiving portion. A second contacting section is defined by an inner surface of the receiving portion for contacting the first contacting section, and a pair of sinuous grooves are defined therein for retaining the lubrication grease. A receiving slot is defined in the second mounting plate for spacing the second contacting section from the second mounting plate to maintain a uniform torque resistance during rotation movements of the second contacting section in different directions.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.